Intangible Assets - Reconciliation of Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Gross carrying cost at beginning of period	$ 68,322	$ 68,322
Gross carrying cost at end of period	68,322	68,322
Accumulated amortization at beginning of period	(40,653)	(38,193)
Amortization expense	(615)	(615)
Accumulated amortization at end of period	(41,268)	(38,808)
Net book value at end of period	$ 27,054	$ 29,514	$ 27,669

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
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- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 928
-SubTopic 340
-Section 50
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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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